This invention relates to styrene copolymer compositions having improved weatherability and color retention performance of an exterior siding of a structure, composite articles utilized for the exterior siding that utilize such compositions, and a method of improving the weatherability and color retention performance of the styrene copolymer compositions. More particularly, this invention relates to weather-resistant and color retaining styrene copolymer compositions, especially acrylonitrile-styrene-acrylate (xe2x80x9cASAxe2x80x9d) compositions, having improved weatherability and color retention, and to multi-layer composites incorporating such compositions. The composite articles are utilized as exterior siding for the structures throughout the building and construction industry.
Two-phase styrene copolymer resins composed of a resin matrix and an elastomeric or rubber component are known to provide a number of useful properties. Illustrative examples are ASA, olefin-styrene-acrylonitrile (OSA) or acrylonitrile-EPDM-styrene resins (AES), and acrylonitrile-butadiene-styrene (ABS). These resins find use in a variety of applications in the building and construction markets (home and commercial siding, window and door profiles, gutters), in leisure and recreation applications (spas, marine components, outdoor furniture, snowmobile components, recreational vehicles, motor homes, campers, etc.) and in the automotive industry (body side moldings, bumpers, interior trim, and mirror housings).
Depending on the particular resin and elastomeric compositions, various performance characteristics are possible. For example, ABS resins generally provide good low temperature impact resistance and processability. ASA and AES resins are particularly known for desirable impact strength, processability and weather resistance, that is, physical property retention and relatively acceptable color retention after significant outdoor exposure.
The prior art has long desired to provide styrene copolymer resins and/or compositions which possess the preceding advantageous physical and performance characteristics but exhibit improved weatherability performance and superior color retention. In particular, it would be advantageous to provide ABS, AES and ASA compositions, especially ASA compositions, having improved weatherability performance via superior color retention and desirable performance properties. Such compositions would be of benefit in the building and construction industries, especially with respect to the manufacture of exterior siding.
Previous attempts to provide styrene copolymer compositions having improved weatherability performance and exterior sidings made thereof have been widespread, yet relatively unsuccessful. For instance, these attempts have included the specialized embossing of mold surfaces of the styrene copolymer composition to minimize the effect of color differential, or fade, over exposure. This attempt failed to provide sufficient color retention and was disadvantageous with respect to processing, cost and/or other performance considerations.
A further attempt to improve the performance of styrene copolymer compositions and sidings made thereof has been to increase amounts of ultra-violet (UV) additive packages known in the art. Although some improvement in weatherability performance and color retention were realized, such attempts are exceedingly costly.
A further attempt to improve the weatherability performance has been to increase pigmentation, particularly TiO2, responsible for contributing to the overall opacity, and therefore reflectivity and weatherability, of the resultant exterior siding. This attempt failed to provide sufficient color retention and was disadvantageous because light resistance of TiO2 pigmentation over exposure to weathering was inadequate.
In sum, the prior art attempts detailed above have generally been characterized by one or more disadvantages, especially with respect to the adequacy of color retention over exposure, quality of surface appearance of the resultant exterior siding, cost considerations as in the increased amounts of UV additive packages, ease of manufacturing, ease of processing, and/or the performance properties of the compositions and the resultant exterior siding.
Accordingly, it would be advantageous to provide styrene copolymer compositions, especially ASA compositions, which exhibit desirable performance properties, improved weatherability and color retention performance as compared to traditional styrene copolymer compositions, advantageous cost considerations, and ease of manufacturing and/or processing.
It is also desirable to provide composite articles incorporating such styrene copolymer compositions, especially ASA compositions, which are suitable for use as exterior siding. It is also desirable to provide a method of improving the weatherability and color retention performance of the styrene copolymer compositions, particularly with respect to exterior siding made of such styrene copolymer compositions.
It is an object of this invention to provide styrene copolymer compositions, especially ASA compositions, which exhibit improved weatherability and color retention performance when processed.
It is another object of this invention to provide a method of improving the weatherability and color retention performance of styrene copolymer compositions and exterior siding. More specifically, it is an object of this invention to provide a method of improving the weatherability and color retention of styrene copolymer compositions, especially ASA compositions, which is advantageous with respect to cost and ease of manufacturing.
Finally, it is an object of the invention to provide a composite incorporating the foregoing improved styrene copolymer compositions as an exterior layer. More specifically, it is an object of the invention to provide styrene copolymer compositions, especially ASA compositions, which can be used in the manufacture of weatherable, color-retaining exterior siding composite structures.